A new dog-sized dinosaur that lived underground 99 million years ago has been discovered.
The species, dubbed Fona herzogae, inhabited what is now Utah in the United States.
The area was a large floodplain ecosystem sandwiched between the shores of a massive inland ocean to the east and active volcanoes and mountains to the west at the time, say scientists.
Paleontologists from North Carolina State University and the North Carolina Museum of Natural Sciences unearthed the fossil – and other specimens from the same species – in the Mussentuchit Member of the Cedar Mountain Formation, beginning in 2013.
The preservation of the fossils, along with some distinguishing features, alerted them to the possibility of burrowing as the area 99 million years ago was a warm, wet, muddy environment with numerous rivers running through it.
They describe Fona as a small-bodied, plant-eating dinosaur about the size of a large dog with a simple body plan.
The team says Fona shares several anatomical features with animals known for digging or burrowing, such as large bicep muscles, strong muscle attachment points on the hips and legs, fused bones along the pelvis – likely to help with stability while digging – and hindlimbs proportionally larger than the forelimbs.
There is further evidence that the dinosaur spent time underground, according to the study published in The Anatomical Record.
Study first author Haviv Avrahami said: “The bias in the fossil record is toward bigger animals, primarily because in floodplain environments like the Mussentuchit, small bones on the surface will often scatter, rot away, or become scavenged before burial and fossilization.
“But Fona is often found complete, with many of its bones preserved in the original death pose, chest down with splayed forelimbs, and in exceptionally good condition.
“If it had already been underground in a burrow before death, it would have made this type of preservation more likely.”
Corresponding author Dr. Lindsay Zanno, head of paleontology at the North Carolina Museum of Natural Sciences, said: “Fona skeletons are way more common in this area than we would predict for a small animal with fragile bones.
“The best explanation for why we find so many of them and recover them in small bundles of multiple individuals is that they were living at least part of the time underground.
“Essentially, Fona did the hard work for us, by burying itself all over this area.”
Although the research team has yet to identify the subterranean burrows of Fona, the tunnels and chamber of its closest relative, Oryctodromeus, have been found in Idaho and Montana. The findings support the idea that Fona also used burrows.
The genus name Fona comes from the ancestral creation story of the Chamorro people, who are the indigenous populations of Guam and the Pacific Mariana Islands.
Fo’na and Pontan were brother and sister explorers who discovered the island and became the land and sky.
The species name honors Lisa Herzog, the palaeontology operations manager at the North Carolina Museum of Natural Sciences, for her work in the field.
Avrahami, a Ph.D. student at NC State and digital technician for the new Dueling Dinosaurs program at the Museum, said: “I wanted to honor the indigenous mythology of Guam, which is where my Chamorro ancestors are from.
“In the myth, Fo’na became part of the land when she died, and from her body sprung forth new life, which to me, ties into fossilization, beauty, and creation.
“Fona was most likely covered in a downy coat of colorful feathers.
“The species name is for Lisa Herzog, who has been integral to all this work and discovered one of the most exceptional Fona specimens of several individuals preserved together in what was likely a burrow.”
The research team believes Fona is key to expanding our understanding of Cretaceous ecosystems.
Avrahami said: “Fona gives us insight into the third dimension an animal can occupy by moving underground.
“It adds to the richness of the fossil record and expands the known diversity of small-bodied herbivores, which remain poorly understood despite being incredibly integral components of Cretaceous ecosystems.”
Zanno said: “People tend to have a myopic view of dinosaurs that hasn’t kept up with the science.”
She added: “We now know that dinosaur diversity ran the gamut from tiny arboreal gliders and nocturnal hunters, to sloth-like grazers, and yes, even subterranean shelterers.”
Produced in association with SWNS Talker
